Loudspeaker



F. L. CREAGER LOUDSPEAKER April 25,l 1939.

Filed NOV. 30,. 1934 www Patented Apr. 25, 1939 UNITED STATES `PATENT OFFICE LOUDSPEAKER Delaware Application November 30, 1934, Serial No. 755,408

3- Claims.

My invention relates to improvements in loudspeakers.

One of the objects of my invention is to provide an improved construction for loudspeakers which have a rel-atively small field coil and cone, and which are adaptable, particularly, for use in the so-called midget radio receivers.

Another object of my invention is to provide an improved construction for loudspeakers whereby it is feasible to make the cone housing, the yoke and the yok-e plate from sheet metal and assemble these parts together at a relatively small cost.

Another object of my invention is to provide an improved construction for loudspeakers which h-as advantages over those proposed heretofore in the way of simplicity and cheapness of construction, and whose operating characteristics satisfy present-day requirements for reception.

Other objects and advantages will hereinafter appear.

In accordance with my invention, the cone housing, the yoke, and the yoke plate, constituting three p-arts of the loudspeaker, are formed from sheet metal. Two of these parts are formed integrally from a single sheet of ferrous material. The yoke plate has a press t Within the yoke, and is disposed at the juncture of the latter with the cone housing. rIhe yoke plate is provided with a central opening into which the end of the core extends to provide an annular air gap, and is provided with an annular flange which extends around this end of the core to increase the magnetic path so that it embraces fully the range of movement of the voice coil.

My invention resides in the improved construction of the character hereinafter described and claimed.

For the purpose of illustrating my invention, an embodiment thereof is shown in the drawing, wherein Figure 1 is a sectional View, taken in a plane through the longitudinal axis of a loudspeaker constructed in accordance with my invention;

Fig. 2 is a fragmentary sectional view similar to Fig. 1, showing a modication;

Fig. 3 is a fragmentary section-al View, showing one of the details of construction;

Figs. 4 and 5 are views similar to Fig. 2, showing other modications;

Fig. 6 is a fragmentary view similar to Fig. 4, showing another modification; and

Fig. 7 is a sectional view, the section being taken on the line 1 7 in Fig. 6

In Fig. l, the reference numerals l0, I2 and i4 designate three parts of the loudspeaker, these being, respectively, the cone housing, the yoke, and the yoke plate.

The yoke is provided with a core I6 extending outwardly from the base i8 of the yoke. In assembling the parts, it is proposed to interpose a flux plate, in the for mof a washer 20 of permeable material, between the base portion of the yoke and the coil 22, if it is desired that the thickness of material in this region be greater than that of the yoke.

Prior to assembly on the yoke, the core I6 is provided with a shading coil in the form of a copper washer 24. This Washer is originally conical, as shown in Fig. 3, and is flattened out between two members 26 and 28 which are moved together for this purpose, whereby the inner edge of the washer is caused to fit within an annular groove Bil in the core, as shoWn in Fig. 1.

A felt washer 3l and a fiber washer 32, each having a snug fit on the core I6, are disposed.

on the latter with the coil 22, as shown. The threaded end of the core extends through the base portion i8 of the yoke and receives a nut 33 which holds the various parts together. The felt washer 3| is compressed slightly between the fiber washer 32 and the coil, and operates to prevent movement of the latter on the core I6. The ber washer has a snug or press fit Within the yoke l2, and serves to center the core I6 in the latter. This washer may be provided with a notch 3F: in its edge for the admission of sealing material into the yoke to completely encase and protect the coil. The terminals of the coil may be led out through the wall of the yoke, as will be well understood.

The yoke plate i4 is shown provided at its inner and outer edges with annular flanges 35 and 36, respectively, these extending in opposite directions. The yoke plate has a press fit within the yoke l2 adjacent the juncture of the yoke and the cone housing l0.

The end of the core i6 extends into the central opening with which the yoke plate is provided, to form an annular air gap in which the voice coil 38 moves. The voice coil is xed on the smaller endof a cone 4i) which is supported at its base by a exible piece 42 clamped between a ring 54 and the outer edge of the cone housing i0. The cone is supported at its smaller end by a yieldable piece 45 fixed to the core extension Il? by a screw 48.

The inner annular flange 35 with which the yoke plate is provided serves the important purpose of extending the magnetic path in the region of motion of the voice coil.

In Fig. 1, the cone housing and the yoke plate are shown formed from a single sheet of ferrous material. The yoke I2 iso heavier gauge than the cone housing and the yoke plate, and is in the form of a cup, drawn from a sheet of ferrous material.

If it is convenient or desirable to make the yoke of the same gauge material as the cone housing, it is proposed to form these two parts integrally, from a single sheet of ferrous material. This construction is shown in Fig. 2, Where the reference characters Illa, 12a and I4a designate, respectively, the cone housing, the yoke, and the yoke plate. The yoke plate, as before, has a press t Within the yoke, being disposed at the juncture of the latter with th-e cone housing. The construction in Fig. 2, otherwise, is the same as that of Fig. 1.

In Fig. 4, the yoke plate |411 is provided with the flanges 35h' and 35h corresponding, respectively, to the anges 35 and 36 in Fig. 1. These ilanges, in Fig. 4, extend in the same direction, the ange 35h operating to increase the magnetic path in which the voice coil moves. The construction, otherwise, is the same as in Fig. 1.

In Fig. 5, the yoke plate Mc is U-shape in cross section, to provide the inner flange 35e and the outer flange 36o extending in the same direction, toward the base portion of the yoke I2C. The yoke plate and the cone housing Io in this construction are made separately from sheets of ferrous material, and are secured together by rivets 50. The inner flange 35e of the yoke plate serves to extend the magnetic path for the Voice coil, in the same manner as the corresponding flanges in Figs. l, 2 and 4. The construction, otherwise, is the same as in Fig. 1.

In the modification shown in Figs. 6 and 7, the yieldable piece 46 and the core extension 41 in Fig. 1 are omitted, and, in lieu thereof, the cone 40 is supported at its smaller end by a yieldable piece 52 extending across the cone housing and having its ends xed to portions 54 stuck out from the latter. This modified construction may also be embodied in the modications shown in Figs. 2, 4 and 5.

It will be understood that various modifications, other than those shown, are possible without departing from the spirit of my invention or the scope of the claims.

I clam as my invention:

1. A loudspeaker comprising a yoke part formed from a single sheet of ferrous material, a cone-housing part and a yoke-plate part formed integrally from a single sheet of ferrous material, said yoke-plate part frictionally tting Within said yoke part adjacent the juncture thereof with said cone-housing part, said friction t constituting the sole means of uniting said yoke-plate part with said yoke part.

2./A loudspeaker comprising a cone housing, a yoke provided with a core, and a yoke plate formed from a single sheet of ferrous material and associated with said cone housing and said yoke, said yoke plate being provided with flanges at its inner and outer edges and directed respectively in opposite directions, the flange at the outer edge of said yoke plate fitting Within said yoke adjacent the juncture of the latter with said cone housing, and the flange at the inner edge of said yoke plate extending around said core at the end of the latter.

3. A loudspeaker comprising a cone-housing part, a yoke part provided with a core, and a yoke-plate part associated with said cone-housing part and said yoke part, two of said three parts being formed integrally from a single sheet of ferrous material, the third one of said three parts being formed from a single sheet of ferrous material, said yoke-plate part being provided With ilanges at its inner and outer edges, the flange at the outer edge of said yoke-plate part tting Within said yoke part adjacent the juncture of the latter with said cone-housing part, and the flange at the inner edge of said yoke-plate part extending around said core at the end of the latter.

FREDERICK L. CREAGER. 

